The demand for degreasing formulations for a myriad of cleaning applications is well known. Target applications range from the light cleaning of printed electronic circuit boards to the cleaning of used automotive parts. Many formulations for these purposes contain varied levels of volatile solvents to efficiently degrease surfaces. Many heavy duty degreasing operations use heated solvent baths.
Recent concerns for environmental and toxicological effects of solvents and solvent baths have caused a full search for aqueous degreasing systems without solvent. Few surfactant based systems have been successful without at least a minor amount of solvent, for the dual purpose of cleaning and defoaming. Hence, industrial and institutional cleaning operations that require degreasing must compromise their desire to be socially conscious to remain effective.
The use of glycol ether solvents or cycloalkanes, in combination with anionic and/or nonionic surfactants, are known in the art. Examples of such systems may be found in Wittel et al., EP 376367; Kao Corporation, JP 3062896; Lyubarskay et al., SU 1300041; Bedo et al., SU T56873; and Dudesek et al., CS 8105867.
Bobsein and Bresson, U.S. Pat. No. 4,663,082 teach a water based cleaning technology based on a series of anionic surfactants, builders and alkalinity agents. Thus, a high pH is required with U.S. Pat. No. 4,663,082 in order to clean effectively. In addition, the patentees teach the use of phosphate builders and chelating agents.
Henkel AG World Organization Patent No. 91/10718 requires at least one anionic surfactant and at least one monocarboxylic acid.
European Patent No. 0392394A1 issued to the Nippon Paint Co. of Japan teaches the use of a surfactant package that requires an alcohol alkoxylate with a phosphate ester. This mix is combined with a necessary amount of alkali builder of varying types. Phosphate esters are notorious for increasing the generation of foam. Also, phosphate esters also contain residual phosphorous, an environmental concern. The nominal amount of alkali builder results in a caustic solution.
Finally, European Patent No. 0084411A1 assigned to Albright & Wilson Limited teaches the use of a wide variety of nonionic surfactants or a phosphate ester with a necessary amount of an alkanolamide and solvent.
What is needed in the art is an effective aqueous based degreaser composition that can be utilized in industrial degreasing operations which utilize elevated cleaning solution temperatures and high spray pressures. This formulation should be solvent free, contain no alkalinity or chelating agents, and should also be low foaming.